China has voiced its opposition to "provocative military acts" on the Korean peninsula after the North escalated tensions by shelling the South earlier this week.

Officials in Beijing have also criticised plans for a US-South Korean joint naval exercise in response to the North's deadly artillery barrage on the island of Yeonpyeong on Tuesday.

Seen as one of the North's closest diplomatic allies, China made its first comments today on the attacks which left two South Korean marines and two civilians dead.

The comments come as a North Korean military official warned of more attacks if there was any more South Korean "provocation".

Chinese premier Wen Jiabao has urged all sides to show restraint.

"China is firmly committed to maintaining the peace and stability of the Korean peninsula and opposes any provocative military acts," he said in a statement.

Governments around the world, including Australia's, have called on China to put more pressure on North Korea to prevent similar attacks in the future.

But China's foreign minister, Yang Jiechi, has also cancelled this week's planned trip to South Korea.

The cancellation has been officially blamed on scheduling issues, but many observers say it is because of the current tension between the two Koreas.

Mr Wen says the current situation is "grim and complicated".

"Relevant sides should maintain the utmost restraint and the global community should do more to relax the tense situation," he said.

The United States and South Korea yesterday announced they would launch a four-day joint naval show of force beginning on Sunday that will involve a US aircraft carrier in a bid to deter the North.

China says it does not support the exercise, saying it will just inflame the situation.

But the Obama administration says it will not be intimidated by North Korea.

The nuclear-powered aircraft carrier, the USS George Washington, which carries 6,000 troops and 75 planes, is being moved into position to take part in the exercise.

Although the exercise was pre-planned before the recent attacks, the US says it will potentially beef it up.

Threat of retaliation

South Korea has ordered extra troops be deployed on islands near the North.

The parliament in Seoul has overwhelmingly voted in favour of a resolution condemning North Korea's shelling, but stopped short of demanding immediate retaliation.

The resolution, carried 261-1 with nine abstentions, also demanded the North apologise for the attack.

South Korea's military will also revise its rules of engagement to respond more strongly to North Korean attacks.

Ground forces will be "drastically" reinforced, including those on five frontline islands near the disputed Yellow Sea border.

But a North Korean military official says the South is to blame for the attack because it fired into the North's maritime territory during an exercise, a charge denied by Seoul.

"If the warmongering South Korean puppets fail to return to their senses and commit another reckless military provocation, our army will carry out second and third rounds of powerful, physical, retaliatory strikes without hesitation," the official said.

He also says the US is partly to blame for the current hostilities because it drew up the "illegal" sea border in the aftermath of the 1950-53 Korean War.

"The West Sea of Korea (Yellow Sea) has become a flashpoint, where the risk of confrontation and clashes between the North and the South is persistent just because the US unilaterally drew the illegal Northern Limit Line," he said.

The North refuses to recognise the Northern Limit Line drawn by US-led United Nations forces at the end of the war.

Moscow's words and actions — including the alleged poisoning of a former spy — are not the results of random aggression but rather fall into distinct patterns that can help us anticipate Russia's next moves under Vladimir Putin.